“To allow a broadcasting company to air such a blatantly partisan attack in lieu of regular programming,” the letter said, “and to classify that attack as ‘news programming’ … would violate the spirit and, we think, the text of current law and regulation.”

Sinclair’s offer to Sen. Kerry to join in a panel discussion following the docu would not satisfy federal-broadcasting fairness rules because the offer is “a transparent attempt to circumvent the fine print of the law and proceed with this partisan plan,” the letter said.

Phone calls to the FCC, whose offices were closed for Columbus Day, and to Sinclair Broadcasting were not returned.

Sinclair has ordered all of its 62 owned stations to preempt the programming of their networks and run the 42-minute movie “Stolen Honor: Wounds That Never Heal” between Oct. 21 and Oct. 24. The movie takes aim at the youthful Kerry’s testimony before the U.S. Senate in 1971, when he talked about alleged atrocities committed by American soldiers during the Vietnam War.

Many veterans were infuriated by that testimony, and the docu interviews a few of them, including at least one who appeared in TV ads for the Swift Boat Veterans for Truth, which claim that Sen. Kerry didn’t earn his medals for service during the Vietnam War.

The worry by Democrats is that the docu could sway undecided voters in swing states like Ohio, Florida and Pennsylvania, where Sinclair owns a number of TV stations.

The broadcast networks declined to comment for the record on the Sinclair matter. But privately they were deeply unhappy over a major station group’s airing a docu unfavorable to one candidate for president within a week of Election Day.